PMM-11686 Query namespace mapping. (#141)

* PMM-11686 Add extended print of errors.

* PMM-11686 Error log level.

* PMM-11686 Logger.

Author: JiriCtvrtka

cmd/postgres_exporter/namespace.go

@@ -233,7 +233,7 @@ func queryNamespaceMappings(ch chan<- prometheus.Metric, server *Server) map[str
 		// Serious error - a namespace disappeared
 		if err != nil {
 			namespaceErrors[namespace] = err
-			level.Info(logger).Log("err", err)
+			level.Error(logger).Log("err", err)
 		}
 		// Non-serious errors - likely version or parsing problems.
 		if len(nonFatalErrors) > 0 {

cmd/postgres_exporter/server.go

@@ -126,6 +126,10 @@ func (s *Server) Scrape(ch chan<- prometheus.Metric, disableSettingsMetrics bool
 	errMap := queryNamespaceMappings(ch, s)
 	if len(errMap) > 0 {
 		err = fmt.Errorf("queryNamespaceMappings returned %d errors", len(errMap))
+		level.Error(logger).Log("msg", "NAMESPACE ERRORS FOUND")
+		for namespace, err := range errMap {
+			level.Error(logger).Log("namespace", namespace, "msg", err)
+		}
 	}
 
 	return err